OCR GCSE PHYSICS P7

A SOLAR DAY is 24hrs

A SIDEREAL DAY is 24hrs and 56mins

a solar day is 4 minutes longer than a sidereal

THE MOON TAKES 24hrs and 49mins to appear in the same part of the sky.

IT TAKES 28 DAYS TO COMPLETE ONE ORBIT!!!

• A SOLAR ECLIPSE IS WHEN THE MOON LINES UP EXACTLY WITH THESUN AND THE EARTH AND BLOCK SUNLIGHT FROM REACHING THE EARTH.

• A LUNAR ECLIPSE IS WHEN THE EARTH'S SHADOW STOPS THE SUNLIGHT FROM REACHING THE EARTH(THE MOON APPEARS RED)

• POWER(dioptres) =1 / focal length(metres)
• MAGNIFICATION = FO/FE
• 1 ARCSECOND= 1/3600
• DISTANCE(pc) = 1/ angle in arcseconds
• SPEED OF RECESSION(kms) =HUBBLE CONSTANT (s)*DISTANCE(km)